Getting error when i use a self define function in a for loop

I wrote a self define function to find a specific string in a given string, the function name is FindNumInStr.

function num=FindNumInStr(InputStr,Target)
    s=num2cell(char(InputStr));
    LengthT=length(char(Target));
    t=0;
    for i=1:length(s)
        if  [s{i:i+LengthT-1}]==Target
            NumStartLocation=i+LengthT-1+2;
            t=1;
        end
        if  t && (s{i}==' ' || i==length(s))
            if i==length(s)
                NumEndLocation=i;
            else
                NumEndLocation=i-1;
            end
            break
        end
    end
    num=str2double([s{NumStartLocation:NumEndLocation}]);
end

When InputStr="fRC Ll=3 Ls=2 TLl=9 TLs=4" and Target="TLs", I can get a num return by the function is 4.

I'm trying to use it in my script. I got a header_array which is 1x704 string, the function work perfect when i do

k=681;
T=FindNumInStr(header_array(k),"TLs");

i can get

T=4

but when i use the function as below

TLs_array=[];
for k=1:length(header_array)
    TLs_array=[TLs_array,FindNumInStr(header_array(k),"TLs")];
end

I get error:

Index exceeds the number of array elements. Index must not exceed 25.
Error in FindNumInStr (line 6)
        if  [s{i:i+LengthT-1}]==Target

How can I fix this problem?

[Bhanu Prakash]

Hi Chia,

Can you provide the "header_array", so that the error can be reproduced at my end?

[chia ching lin]

Hi Bhanu, here is the header_array

Answer 1

[VBBV]

As the error states, Index exceeds the number of array elements. Index must not exceed 25.

the length of InputStr is 25, you need to modify the for loop as shown below for the same reason when you try to access an element which is beyond the limit specified in array.

k=681;
InputStr="fRC Ll=3 Ls=2 TLl=9 TLs=4" 

InputStr = "fRC Ll=3 Ls=2 TLl=9 TLs=4"

s=num2cell(char(InputStr))

s = 1×25 cell array
  Columns 1 through 22

    {'f'}    {'R'}    {'C'}    {' '}    {'L'}    {'l'}    {'='}    {'3'}    {' '}    {'L'}    {'s'}    {'='}    {'2'}    {' '}    {'T'}    {'L'}    {'l'}    {'='}    {'9'}    {' '}    {'T'}    {'L'}

  Columns 23 through 25

    {'s'}    {'='}    {'4'}

% length of InputStr
length(s)

ans = 25

% length of Target
LengthT=length(char("TLs"))

LengthT = 3

% for loop limit 
length(s)+LengthT-1

ans = 27

function num=FindNumInStr(InputStr,Target)
    s=num2cell(char(InputStr));
    LengthT=length(char(Target));
    t=0;
    % check by modifying for loop as below 
    for i=1:length(s)-2
        if  [s{i:i+LengthT-1}]==Target
            NumStartLocation=i+LengthT-1+2;
            t=1;
        end
        if  t && (s{i}==' ' || i==length(s))
            if i==length(s)
                NumEndLocation=i;
            else
                NumEndLocation=i-1;
            end
            break
        end
    end
    num=str2double([s{NumStartLocation:NumEndLocation}]);
end

[chia ching lin]

Hi @VBBV, thanks for answering, but the function success when InputStr is one at a time. It only fail when I call the function inside the for loop of my script.

[VBBV]

The code seems to work when you modify the for loop as below

data = load('header_array.mat')

data = struct with fields:
    header_array: ["fRC Ll=2 Ls=1 TLl=0 TLs=0"    "cRC Ll=2 Ls=1 TLl=0 TLs=0"    "fRC Ll=2 Ls=1 TLl=0 TLs=1"    "cRC Ll=2 Ls=1 TLl=0 TLs=1"    "fRC Ll=2 Ls=1 TLl=0 TLs=2"    …    ]

data.header_array(:)

ans = 704×1 string array
    "fRC Ll=2 Ls=1 TLl=0 TLs=0"
    "cRC Ll=2 Ls=1 TLl=0 TLs=0"
    "fRC Ll=2 Ls=1 TLl=0 TLs=1"
    "cRC Ll=2 Ls=1 TLl=0 TLs=1"
    "fRC Ll=2 Ls=1 TLl=0 TLs=2"
    "cRC Ll=2 Ls=1 TLl=0 TLs=2"
    "fRC Ll=2 Ls=1 TLl=0 TLs=3"
    "cRC Ll=2 Ls=1 TLl=0 TLs=3"
    "fRC Ll=2 Ls=1 TLl=0 TLs=4"
    "cRC Ll=2 Ls=1 TLl=0 TLs=4"
    "fRC Ll=2 Ls=1 TLl=0 TLs=5"
    "cRC Ll=2 Ls=1 TLl=0 TLs=5"
    "fRC Ll=2 Ls=1 TLl=0 TLs=6"
    "cRC Ll=2 Ls=1 TLl=0 TLs=6"
    "fRC Ll=2 Ls=1 TLl=0 TLs=7"
    "cRC Ll=2 Ls=1 TLl=0 TLs=7"
    "fRC Ll=2 Ls=1 TLl=1 TLs=0"
    "cRC Ll=2 Ls=1 TLl=1 TLs=0"
    "fRC Ll=2 Ls=1 TLl=1 TLs=1"
    "cRC Ll=2 Ls=1 TLl=1 TLs=1"
    "fRC Ll=2 Ls=1 TLl=1 TLs=2"
    "cRC Ll=2 Ls=1 TLl=1 TLs=2"
    "fRC Ll=2 Ls=1 TLl=1 TLs=3"
    "cRC Ll=2 Ls=1 TLl=1 TLs=3"
    "fRC Ll=2 Ls=1 TLl=1 TLs=4"
    "cRC Ll=2 Ls=1 TLl=1 TLs=4"
    "fRC Ll=2 Ls=1 TLl=1 TLs=5"
    "cRC Ll=2 Ls=1 TLl=1 TLs=5"
    "fRC Ll=2 Ls=1 TLl=1 TLs=6"
    "cRC Ll=2 Ls=1 TLl=1 TLs=6"

H = length(data.header_array)

ans = "fRC Ll=3 Ls=2 TLl=9 TLs=4"

H = 704

k=681;
InputStr="fRC Ll=3 Ls=2 TLl=9 TLs=4" 

InputStr = "fRC Ll=3 Ls=2 TLl=9 TLs=4"

Target = "TLs"

Target = "TLs"

% s=num2cell(char(InputStr))
% length of InputStr
% length(s)
% length of Target
% LengthT=length(char("TLs"))
% for loop limit 
% length(s)+LengthT-1
k=681;
% T=FindNumInStr(data.header_array(k),"TLs")

TLs_array=[];
for k=1:H
    TLs_array=[TLs_array,FindNumInStr(data.header_array(k),"TLs")];
end
TLs_array.'

ans = 704×1

0 0 1 1 2 2 3 3 4 4

function num=FindNumInStr(InputStr,Target)
    s=num2cell(char(InputStr));
    LengthT=length(char(Target));
    t=0;
    % check by modifying for loop as below 
    for i=1:length(s)-2
        if  [s{i:i+LengthT-1}]==Target
            NumStartLocation=i+LengthT-1+2;
            t=1;
        end
        % similarly this change
        if  t & (s{i}==' ' || i+2==length(s))
            % this change
            if i+2==length(s)
                NumEndLocation=i+2;
            else
                NumEndLocation=i-1;
            end
            % break
        end
    end
    num=str2double([s{NumStartLocation:NumEndLocation}]);
end

Please see the change done to these lines

 for i=1:length(s)-2
        if  [s{i:i+LengthT-1}]==Target
            NumStartLocation=i+LengthT-1+2;
            t=1;
        end
        % similarly this change
        if  t & (s{i}==' ' || i+2==length(s))
            % this change
            if i+2==length(s)